Bulk food processor with angled axial flow fan

ABSTRACT

Apparatus and methods for bulk processing items on a conveyor belt using an angled axial fan that extends obliquely into a processing chamber and includes a curved back wall forming an air flow chamber. The angled axial fan enhances air flow around a product being processed on the conveyor belt. A heater employs shrouds and a series of baffle plates held together using a connecting pin to heat circulated air in a low-pressure area below the conveyor belt. Baffles in an upper chamber mix and direct heated, circulated air over the conveyed product.

BACKGROUND

The invention relates generally to a processor for articles, such asfood articles, and more particularly to apparatus and methods forpasteurizing food.

In preparing foods or other items in bulk, the items may be conveyedthrough a processing chamber using a conveyor belt. A process, such asheating, cooling or steaming of the articles may be performed. Forexample, it may be desirable to pasteurize nuts, such as almonds, inbulk using a conveyor belt. Pasteurization may involve heating and—orcooling the nuts using heated or cooled air circulated over the conveyednuts. It may be desirable to enhance the flow of air in certainprocessing chambers to make the processing of articles more efficient.

SUMMARY

A bulk food processor employs an angled axial flow fan to circulate airover a product conveyed through a processing chamber. Product isconveyed through the processing chamber by a conveyor belt and heatedair is circulated to process the product. The angled axial fan has acurved rear wall to facilitate air flow. A heater employs shrouds and aseries of baffle plates held together using a connecting pin to heatcirculated air in a low-pressure area below the conveyor belt. Bafflesin an upper portion of the processing chamber mix and direct heated,circulated air over the conveyed product.

According to one aspect, a bulk processor for an item comprises aprocessing chamber having a product inlet and a product outlet, aconveyor for conveying product through the processing chamber from theproduct inlet to the product outlet and an axial flow fan forcirculating air around the product. The axial flow fan has a curved backwall forming an air flow chamber for directing air from below theconveyor to a high-pressure region above the conveyor.

According to another aspect, a bulk processor comprises a processingchamber having a product inlet and a product outlet, a conveyorextending longitudinally through the processing chamber for conveyingproduct through the processing chamber from the product inlet to theproduct outlet, a fan for circulating air from below the conveyor to ahigh-pressure region above the conveyor and a plurality of bafflesextending longitudinally above the conveyor for mixing the circulatedair and directing an even flow of air over the conveyor.

According to still another aspect, a bulk processor for an itemcomprises a processing chamber having a product inlet and a productoutlet, a conveyor for conveying product through the processing chamberfrom the product inlet to the product outlet, a fan for circulating airfrom below the conveyor to a high-pressure region above the conveyor anda heater below the conveyor for heating air circulated by the fan. Theheater comprises a natural gas burner comprising a housing mountedoutside of the processing chamber, a flame tube extending from thehousing through a side wall of the processing chamber into an interiorof the processing chamber, openings to allow air intake to the flametube from outside the processing chamber, an inner shroud surroundingthe flame tube and having peripheral openings, and an outer shroudsurrounding the inner shroud.

According to yet another aspect, an axial fan for circulating aircomprises an air flow chamber, a shroud connected to the air flowchamber and a propeller mounted in the shroud for generating air flow.The propeller comprises a front hub plate facing the processing chamber,the front hub plate having a central opening for receiving an axle and aplurality of radiating petals, a rear hub plate having a central openingfor receiving the axle and a plurality of radiating petals, and aplurality of radiating blades, each blade attached at a first side edgeto a petal of the front hub plate and attached at a second side edge toa petal of the rear hub plate.

According to still another aspect, a door for a bulk processor forprocessing items comprises a base member configured to couple to aprocessing chamber and having an opening and an axial fan mounted in theopening. The axial fan comprises a shroud protruding from an inside wallof the base member and housing a propeller, and an air flow chamberextending from the shroud for directing air flow generated by thepropeller, a portion of the air flow chamber extending from an outsidewall of the base member and a portion of the air flow chamber extendingfrom an interior wall of the base member.

According to another aspect, a heater for heating air comprises a flametube extending from a housing for combusting fuel to generate heat, aninner shroud surrounding a first end of the flame tube and havingperipheral openings, an outer shroud surrounding the inner shroud and aseries of baffle plates between an outlet of the inner shroud and anoutlet of the outer shroud for mixing air heated by the flame tube.

In another aspect, a bulk processor with a processing chamber, conveyorand air circulator includes an exhaust for selectively exhausting airfrom the processing chamber, the exhaust having an inlet below theconveyor.

BRIEF DESCRIPTION OF THE DRAWINGS

These features and aspects of the invention, as well as its advantages,are described in more detail in the following description, appendedclaims, and accompanying drawings, in which:

FIG. 1 is a side view of a bulk food processor according to anembodiment of the invention;

FIG. 2 is an opposite side view of the bulk food processor of FIG. 1 ;

FIG. 3 is a cross-sectional side view of the bulk food processor of FIG.1 ;

FIG. 4 is a cross-sectional front view of the bulk food processor ofFIG. 1 ;

FIG. 5 is an isometric view of a door of the bulk food processor of FIG.1 containing an angled axial fan;

FIG. 6 is a side view of the door of FIG. 5 ;

FIG. 7 is an isometric rear view of the door of FIG. 5 ;

FIG. 8 is a top view of the door of FIG. 5 ;

FIG. 9 is an isometric front view of the propeller portion of the axialfan of FIG. 5 ;

FIG. 10 is an isometric rear view of the propeller portion of FIG. 9 ;

FIG. 11 is a side view of the propeller portion of FIG. 9 ;

FIG. 12 is a detailed view of the front hub plate of the propellerportion of FIG. 9 ;

FIG. 13 is an isometric front view of the door of the bulk foodprocessor with the propeller portion of the axial fan removed;

FIG. 14 is an isometric exterior view of the heater of the bulk foodprocessor of FIG. 2 ;

FIG. 15 is an isometric interior view of the heater of FIG. 14 ;

FIG. 16 is a cross-sectional view of the heater of FIG. 14 ;

FIG. 17 is a front view of the heater of FIG. 14 ;

FIG. 18 is an isometric view of the air flow plate of the heater of FIG.14 ;

FIG. 19 is a front view of the first baffle plate of the heater of FIG.14 ;

FIG. 20 is a front view of the second baffle plate of the heater of FIG.14 ;

FIG. 21 is a front view of the third baffle plate of the heater of FIG.14 ;

FIG. 22 is a front view of the fourth baffle plate of the heater of FIG.14 ; and

FIG. 23 is an isometric view of a connecting pin of the heater of FIG.14 .

DETAILED DESCRIPTION

A processor 10 that operates according to and embodies features of theinvention is shown in FIGS. 1-4 . The processor 10 changes thetemperature of an item conveyed through the processor. For example, theprocessor can be used to raise the temperature of nuts beingpasteurized, pasteurize nuts using steam, dry pasteurized nuts, coolpasteurized nuts or perform any suitable process on any suitablearticle, not limited to nuts.

The illustrative processor 10 comprises a chamber 30 with an entrance 31for items to be processed at one end and an exit 32 for the processeditems at an opposite end. A conveyor belt 20 receives items at theinfeed 11 of the conveyor belt and conveys the items along a processingpath, where a process, such as heating, cooling or steam pasteurizing,is performed on the items. The processed product exits the chamber atexit 32 and the conveyor belt reverses at outfeed 12 to return to theinfeed via a returnway path. In one embodiment, the belt is a foraminousbelt with sufficient opening to allow airflow therethrough. The conveyorbelt 20 is trained around drive 14 and idle sprockets 16 at oppositeends of an upper carryway that traverses the processor, and driven by amotor or other suitable drive. Diverting rollers or drums 24 or otherguides guide the endless conveyor belt 20 along a returnway below thecarryway. The illustrative returnway is outside of and below the chamber30, but the invention is not so limited. The conveyor belt may includerepositioning flips formed by repositioning rollers (not shown) alongthe upper carryway, as described in U.S. Pat. Nos. 8,028,618 and5,410,951, the contents of which are herein incorporated by reference.The invention is not limited to the illustrative conveyor belt and anysuitable means can be used to convey articles through the processor,even conveyors without endless conveyor belts.

The processing chamber 30 includes a plurality of air circulators, shownas axial flow fans 50, for circulating air along an air flow path thatintersects items being conveyed atop the conveyor belt 20 along thecarryway. The illustrative conveyor belt 20 is foraminous to allow theair to pass through. Other features of such a processor as describedthus far are given in U.S. Pat. No. 6,274,188, “Method for Steam-CookingShrimp at Reduced Temperatures to Decrease Yield Loss,” Aug. 14, 2001,and PCT Published Application Number WO 2015/133981, entitled“Low-Temperature, Forced-Convection, Steam-Heating of Nuts”, and U.S.Provisional Patent Application No. 62/365,086 entitled “Bulk FoodProcessor with Angled Fan”, all of which are incorporated herein byreference. One example of such a cooker is the CoolSteam® cookermanufactured and sold by Laitram Machinery, Inc., of Harahan, La.,U.S.A.

The axial flow fan 50, driven by a motor 51, pulls air from a lowerregion 33 below the conveyor belt 20, and pushes air up into an air flowchamber 53 on the side of the processing chamber 30. As used herein, anaxial flow fan, or an axial fan, as opposed to a radial or centrifugalfan, refers to an air circulator that causes air to move in a directionparallel to the shaft about which the fan blades rotate. However, theprocessor is not limited to an axial fan, and any suitable aircirculator, including, but not limited to, radial or centrifugal fans,may be used to circulate air or another fluid through the illustrativeprocessing chamber 30.

The illustrative air flow chamber 53 extends up the side of theprocessing chamber 30, forming a portion of the side wall of theprocessing chamber 30. The illustrative axial flow chamber 53 includesportions within the processing chamber 30 and portions that extendbeyond the side wall of the processing chamber.

The top of the processing chamber 30 can shaped to direct the airflowover the product on the conveyor belt 20. The region 34 above theconveyor belt forms a high pressure region, while the region below theconveyor belt 20 forms a lower pressure region 33. Air is pushed throughthe foraminous conveyor belt 20 into the low-pressure region 33 belowthe conveyor belt and continues to circulate to process conveyedproduct. The processing chamber 30 also includes an exhaust 64 forreleasing air to the ambient, if necessary.

In one embodiment, the exhaust 64 pulls air from the bottom chamber 33,i.e., the low-pressure region of the chamber 30. The illustrative inletto the exhaust pipe is below the conveyor belt, so that lower-pressureair is exhausted. The exhaust 64 can be a powered exhaust that pulls airfrom the low-pressure chamber and releases it to the environment using afan or other suitable device, though the invention is not so limited.

The air circulated by the axial flow fan 50 may be heated, cooled, or atambient temperature. In the illustrative embodiment, the processingchamber 30 includes heaters 70 for heating the circulated air, thedetails of which are described below.

The upper, high pressure chamber 34 above the conveyor belt includesbaffles 40, 42 for mixing the circulated air and directing an even flowof air over the conveyor belt 20. In one embodiment, the baffles 40, 42comprise offset sheets of metal connected to and hanging from the top ofthe chamber 30 and extending in a longitudinal direction above theconveyor. Each baffle 40, 42 has a wavy shape, with the crests of afirst baffle 40 offset from the crests of a second baffle 42. In thismanner, some of the air blown by the fan 50 is deflected by the firstbaffle and over the product, some of the air passing through the baffle40 is deflected down by the second baffle 42 and the remaining airpassing through the second baffle 40 is deflected down over the productby the side wall of the chamber 30. While the illustrative baffles 40,42 have a sinusoidal shape, the invention is not so limited. Forexample, the baffles 40, 42 could be perforated sheet metal with offsetopenings, a number of smaller sheets arranged and spaced apart to directair flow or have any other suitable configuration for providing anevenly mixed flow of air over a product. The baffles 40, 42 may have anysuitable location, size and shape and be mounted to any suitablecomponent in the chamber 34.

The illustrative axial flow fan 50, shown in detail in FIGS. 5 through 8, may be mounted in a door 80 of the processing chamber 30 to facilitateaccess to the axial flow fan 50 for cleaning, replacement, repair,testing or any other reason. The illustrative axial flow fan is mountedobliquely in the door 80, with the fan motor 51 extending obliquelythrough the door 80 and into the lower portion of the processingchamber. The axial flow fan 50 and motor 51 may be mounted at anysuitable angle to facilitate airflow through the air flow chamber 53extending from the fan inlet 59 below the conveyor belt 20 to the fanoutlet 52 above the conveyor belt. The illustrative door 80, comprisinga planar base member designed to fit in an opening in the processingchamber and having an opening for mounting the axial flow fan 50, may behingedly or otherwise movably connected to the side wall of the chamber30 and a latch 81 may be used to latch the door in a closed positionduring operation. The door may have any suitable size, shape,configuration and location, and is not limited to the illustrativeembodiment.

In one embodiment, the axial flow fan 50 and motor 51 are tilted inwardat an angle between about 15° and about 45° and preferably about 30°,though the invention is not so limited. The axial flow fan 50 has ashroud 56 that extends to and interfaces with the lower portion 33 ofthe processing chamber 30 at an angle, so that the bottom of the faninlet 59 b is closer to the door 80 than the top of the fan inlet 59 a.The propeller portion 150 of the axial flow fan 50 is mounted at theinlet to the shroud 56 at the oblique angle.

The air flow chamber 53 includes a curved back wall 54 to facilitate airflow. The curved back wall 54 extends beyond the outside wall of theplanar member defining the base of the door 80. The illustrative backwall 54 curves about 180° from the bottom of the door 80 to the top ofthe door. On the inside of the door 80, the top portion of the axialflow chamber 53 extends up and inward at an angle and includes arectangular outlet 52 pointing into the high pressure region 34 at anangle. The outlet 52 may include flow straighteners. The interiorportion of the air flow chamber 53 includes triangular side walls 57extending from an interior wall of the door planar member and an angledfront wall 58 having a lower curved edge intersecting the shroud 56 andan upper edge forming a wall of the outlet 52.

The portion of the air flow chamber that extends outside of the door 80is formed by the curved back wall 54 and shaped side walls 55 connectingthe curved back wall to the door. A cut out in the air flow chamber 53is formed by shaped walls 159 and accommodates the axial fan motor 51.The illustrative cut out has the shape of an upside down, truncated teardrop, but the invention is not so limited. The resulting air flowchamber 53 produces enhanced, well-mixed, even air flow into the upperportion of the processing chamber 34.

FIGS. 9-12 show an embodiment of a propeller portion of the axial fan50. The illustrative propeller portion 150 of the axial fan 50 comprisesa front hub plate 60 facing the lower chamber 33, a rear hub plate 61facing the air flow chamber 53 and a plurality of blades 68 mounted toand extending between front and rear hub plates 60 and 61.

Each hub plate 60, 61 comprises a central opening 62 for receiving andclamping onto an axle from the motor 51. A plurality of petals 63 extendradially and are distributed about the periphery of each hub plate. Asshown in FIG. 12 , each petal 63 comprises a narrow neck 162 and a widerbody defined by a flat side edge 163 including a plurality of openings164 for receiving fasteners, such as rivets, to fasten a blade 68 to thehub plate. A radially outer flat edge 165 transitions to a curved sideedge 167. The curved side edge 167 includes an inner indent 168 foraccommodating a radially inner corner of an adjacent petal flat sideedge.

Each blade 68 comprises a bent rectangular sheet having a flat firstside edge 168 with a radially inner portion fastened to the flat sideedge 163 of a petal 63 of the front hub plate 60 using fasteners, suchas rivets. A second flat side edge 169 of the blade 68 is fastened tothe rear hub plate 61 so that the blade extends at an angle between thetwo hub plates. The front and rear hub plates 60, 61 are arrangedrelative to each other, so that a first side edge 168 of a first blade68 can be mounted to a flat side edge 163 of a petal on the front hubplate 60, while the second side edge 169 of the blade 68 is mounted to aflat side edge 163 of a petal 63 on the rear hub plate 61. The propellerportion of the axial fan 50 is not limited to the propeller 150 shown inFIGS. 9-12 and any suitable fan, including a non-axial fan, may be usedto circulate air in the processor 10.

The axial fan 50 can also include flow straighteners 65, as shown inFIG. 13 . The illustrative flow straighteners 65 are formed of bentsheet metal, but the invention is not so limited. FIG. 13 also shows theaxle 66 extending from the motor through the shroud 56 for driving thepropeller 150.

As described above, the illustrative processor 10 includes a heater 70for heating the circulated air to process a product. FIGS. 14-17 show anembodiment of a suitable heater 70 for heating circulated air, thoughthe invention is not limited to the illustrative heater 70. Theillustrative heater 70 comprises a natural gas burner with flowdistributers mounted in the side wall 130 of the chamber 30 opposite theaxial fan inlet 59, below the conveyor belt. The heater 70 includes ahousing 72 mounted outside the chamber 30 that houses motors, valves,fuel supply and other components required to combust a fuel to generateheat. A flame tube 74, where combustion occurs, extends from the housing72, through the side wall 130 of the processing chamber 30 and into theinterior of the lower portion 33 of the chamber 30. Alternatively, theheater can be mounted in a different location, and is not limited to alocation below the conveyor 20.

The heater 70 further includes an inner shroud 82 for the flame tube 74.An outer shroud 84 surrounds the inner shroud 82, and is longer than theinner shroud, so that the exit of the outer shroud extends farther intothe chamber 30. The shrouds may increase the pressure in the combustionregion of the heater to facilitate combustion. The inner shroud 82 is acylindrical tube forming an inner heat chamber. The inner shroud 82extends inwards from the side wall 130 and has a plurality of peripheralopenings 88 for directing heat into the space between the inner shroudand the outer shroud 84. A heat barrier plate 86 surrounds the flametube and blocks heat from passing back towards the side wall 130. Aseries of baffle plates 90, 92, 94, 96 are arranged between the interiorfacing end of the inner shroud 82 and the interior facing end of theouter shroud 84. The baffle plates include openings to fully mix heatedair from the flame tube 74. Spacing pins 196 connect the baffle plates90, 92, 94, 96 together, as described below.

The processing chamber side wall 130 includes an opening 131 sized andconfigured to mount the outer shroud 84. An air flow plate 76 surroundsthe opening 131 on the exterior of the wall 130 and is mounted to thewall 130 using fasteners 176. An embodiment of the air flow plate 76 isshown in FIG. 18 . An outer mounting plate 78 receives the heaterhousing 72 and connects the heater housing 72 to the air flow plate 76.The outer mounting plate 78 is connected to spacers 79 via fasteners178, and the spacers 79 connect to the air flow plate fasteners 176 tocreate openings 89 for air intake into the interior space within theouter shroud 84. Any suitable means for forming intake openings may beused, and the invention is not limited to the illustrative means. Asdescribed above, the processor includes an exhaust 64 to balance for theair pulled into the chamber via the heater 70.

In one embodiment, the housing 72 and components therein and flame tube74 comprise a compact burner unit available from Max Weishaupt GmbH ofSchwendi, Germany, a burner available from Honeywell Eclipse™ or anotherburner known in the art, though the invention is not so limited. Theheater could comprise any heat source, including, but not limited to, anelectric heat source, a natural gas heat source, a propane heat source,an oil heat source or other available heat source.

Referring to FIG. 18 , the air flow plate 76 comprises a central hub 171having a central opening 172 for receiving the flame tube 74. Thecentral hub 171 includes peripheral slots 174 for receiving mountingtabs of the inner shroud 82. The central hub 171 further includes radialslots 173 for receiving spacing pins 180 (shown in FIG. 16 ) to connectand space the heat barrier plate 86 and the air flow plate 76. Flexiblespokes 179 connect the central hub 171 to an outer rim 177, whichincludes openings 181 for receiving the fasteners 176 to mount the airflow plate 76 to the processing chamber side wall 130 and spacers 79.While the illustrative air flow plate 76, outer mounting plate 78 andheat barrier plate 68 are disc-shaped, the invention is not limited tothe illustrative shape, and the shape can vary, depending in particularon the size and shape of the side wall opening 131.

Referring to FIGS. 19-22 , the baffle plates 90, 92, 94, 96 promote airmixing while protecting the flame tube from contamination. The baffleplates 90, 92, 94, 96 overlap each other and are configured to prevent astraight path through the series of baffle plates. Each plate comprisesa basic disc shape with openings to allow air flow. The openings of eachbaffle plate preferably align with a solid portion of another baffleplate, so that heated air passing through an opening is redirected by asubsequent baffle plate.

A first baffle plate 90, shown in FIG. 19 , has an inner rim 190 withperipheral slots 191 for receiving mounting tabs on the inner shroud 82to mount the first baffle plate 90 to the inner shroud. Outer spokes 192radiate from the inner rim 190 to the inner surface of the outer shroud84 to provide baffling between the inner shroud and outer shroud. Innerspokes 193 extend between the inner rim 190 and center disc 231, formingopenings 194 for airflow. Two of the inner spokes 193 a, 193 b connectto the center disc 231, with an arc-shaped space 232 formed between theinner tips of the other inner spokes 193. In one embodiment, theremaining inner spokes 193 are not connected near the center to allowthe material to expand when exposed to the high temperature from theflame tube 74, but the invention is not so limited. The illustrativecenter disc portion 231 includes an opening holding two thin discs toreduce vibration caused by air flow. Radial slots 195 are provided incertain spokes to receive mounting and spacing pins 196 to connect thebaffle plates 90, 92, 94, 96 together.

Referring to FIG. 20 , a second baffle plate 92 includes a substantiallysolid hub 197, with radial slots 198 for receiving pins 196 and spokes199 radiating from the solid hub 197. The spokes 199 are offset from thespokes 192 of the first baffle plate 92, so that air flowing between thespokes 192 hits the spokes 199, causing mixing of the air.

Referring to FIG. 21 , a third baffle plate 94 comprises a disc having apattern of openings 202 that align with the solid portions of the secondbaffle plate. The open areas of the second baffle plate 92 align withthe solid portions of third baffle plate 94. The third baffle plate alsoincludes radial slots 204 for receiving pins 196 to connect the thirdbaffle plate 94 to the second baffle plate 92.

Referring to FIG. 22 , a fourth baffle plate 96 comprises a central hub206, radiating spokes 208, radial slots 210 and openings 212 in the hub206. The openings 212 are arranged to overlap the solid portions of thethird baffle plate 94.

The radial slots 195, 198, 204, 210 are aligned and sized progressivelysmaller to accommodate connecting pins 196. FIG. 23 shows an embodimentof a connecting pin 196 suitable for joining a plurality of heatercomponents together. The pin 196 comprises a base 220 and a firstconnecting section 221 extending from the base. The first connectingsection 221 is narrower than the base, so as to fit through radial slots195 while the base 220 is larger than the radial slots. A secondconnecting section 222 extends from the first connecting section and isnarrower than the first connecting section 221 so as to fit through theradial slots 198 of the second baffle plate 92. A third connectingsection 223 extends from the second connecting section 222 and isnarrower than the second connecting section so as to fit through theradial slots 204 of the third baffle plate 94. A tip 224 extends fromthe third connecting section 223 and is narrower than the thirdconnecting section so as to fit through the radial slots 210 of thefourth baffle plate 96. Each connecting section includes upper and lowerslits 226 forming locking tabs 228 near the step formed between eachsection.

Referring back to FIG. 16 , the connecting pins 196 hold the baffleplates 90, 92, 94, 96 in position relative to each other. Afterinsertion through a baffle plate, the associated locking tabs 228 arebent in opposite directions to lock the connecting pin relative to thebaffle plate.

The other connecting pins 180 for connecting and spacing the heatbarrier plate 86 and the air flow plate 76 also each includes a base,movable tabs and stepped down connecting sections to lock the air flowplate 76 to the heat barrier plate 86.

In one embodiment, the connecting pins 180, 196 and other components ofthe processor that are exposed to high temperatures may comprise ahigh-temperature metal, such as INCONEL®, available from Special MetalsCorporation of New Hartford, N.Y. The connecting pins 180, 196 may belaser cut to form the desired shapes and configurations.

In one embodiment, a plurality of processors may be used together topasteurize a product, such as almonds or other nuts. A first processorwith an angled axial fan may receive raw almonds from an input, such asa hopper, and circulate warm air over the raw almonds as they areconveyed through the first processor, to pre-heat the almonds. The firstprocessor passes the pre-heated almonds to a second processor having anangled axial fan, which uses steam and air combined and blown by theangled axial fan, to pasteurize the almonds as they are conveyed throughthe second processor. Then, the second processor can pass thepasteurized almonds to a third processor, which can used heated aircirculated using an angled axial fan to dry the pasteurized nuts as theyare conveyed through the third processor. Finally, a fourth processor,which can used cooled air circulated through a cooling chamber by anangled axial fan, cools the pasteurized, dried nuts as they pass throughthe cooling chamber.

The invention is not limited to the illustrative embodiments.

What is claimed is:
 1. A bulk processor for an item, comprising: aprocessing chamber having a product inlet and a product outlet; aconveyor for conveying product through the processing chamber from theproduct inlet to the product outlet; and an axial flow fan forcirculating air around the product, the axial flow fan having a curvedback wall forming an air flow chamber for directing air from alow-pressure region below the conveyor to a high-pressure region abovethe conveyor, over the product on the conveyor and through the conveyorback into the low-pressure region below the conveyor to circulate airover the product.
 2. The bulk processor of claim 1, further comprising aplurality of baffles above the conveyor for mixing the circulated airand directing an even flow of air over the conveyor.
 3. The bulkprocessor of claim 1, wherein the axial flow fan is mounted in a door tothe processing chamber, and the curved back wall extends outside of abase portion of the door.
 4. The bulk processor of claim 3, wherein theaxial flow fan extends obliquely from the door into a lower portion ofthe processing chamber.
 5. The bulk processor of claim 1, wherein thecurved back wall includes a cut out for mounting a motor driving theaxial flow fan.
 6. The bulk food processor of claim 1, wherein a topportion of the air flow chamber extends up and inward at an angle andincludes a rectangular outlet pointing into the high-pressure region atan angle.
 7. The bulk food processor of claim 6, wherein an interiorportion of the air flow chamber includes triangular side walls and anangled front wall having a lower curved edge intersecting a shroud ofthe axial flow fan and an upper edge forming a wall of the rectangularoutlet.
 8. The bulk processor of claim 1, wherein the axial flow fan hasa propeller comprising: a front hub plate facing the processing chamber,the front hub plate having a central opening for receiving an axle and aplurality of radiating petals, a rear hub plate having a central openingfor receiving the axle and a plurality of radiating petals, and aplurality of radiating blades, each blade attached at a first side edgeto a petal of the front hub plate and attached at a second side edge toa petal of the rear hub plate.
 9. The bulk processor of claim 8, whereineach petal comprises a narrow neck and a wider body defined by a flatside edge including a plurality of openings for receiving fasteners tofasten a blade to the hub plate.
 10. The bulk processor of claim 9,wherein each petal further comprises a radially outer flat edge thattransitions to a curved side edge opposite the flat side edge.
 11. Thebulk food processor of claim 10, wherein each radiating blade comprisesa bent rectangular sheet of metal having a first side edge attached to aflat side edge of a petal on the front hub plate, and a second side edgeattached to a flat side edge of a petal on the rear hub plate.
 12. Thebulk processor of claim 1, further comprising a heater below theconveyor for heating air circulated by the axial flow fan.
 13. The bulkprocessor of claim 1, further comprising an exhaust for selectivelydischarging air from the processing chamber.
 14. The bulk processor ofclaim 13, wherein the exhaust employs a powered fan to control airdischarge.
 15. An axial fan for circulating air, comprising: an air flowchamber; a shroud connected to the air flow chamber; and a propellermounted in the shroud for generating air flow, the propeller comprising:a front hub plate facing a processing chamber, the front hub platehaving a central opening for receiving an axle and a plurality ofradiating petals, a rear hub plate having a central opening forreceiving the axle and a plurality of radiating petals, and a pluralityof radiating blades, each blade attached at a first side edge to a petalof the front hub plate and attached at a second side edge to a petal ofthe rear hub plate.
 16. The bulk processor of claim 15, wherein eachpetal comprises a narrow neck and a wider body defined by a flat sideedge including a plurality of openings for receiving fasteners to fastena blade to the hub plate.
 17. The bulk processor of claim 16, whereineach petal further comprises a radially outer flat edge transitions to acurved side edge opposite the flat side edge.
 18. The bulk processor ofclaim 17, wherein the curved side edge includes an inner indent foraccommodating a radially inner corner of an adjacent petal flat sideedge.
 19. The bulk food processor of claim 17, wherein each radiatingblade comprises a bent rectangular sheet of metal having a first sideedge attached to a flat side edge of a petal on the front hub plate, anda second side edge attached to a flat side edge of a petal on the rearhub plate.
 20. A door for a bulk processor for processing items,comprising: a base member configured to couple to a processing chamberand having an opening; and an axial fan mounted in the opening, theaxial fan comprising a shroud protruding from an inside wall of the basemember and housing a propeller, and an air flow chamber extending fromthe shroud for directing air flow generated by the propeller, a portionof the air flow chamber extending from an outside wall of the basemember and a portion of the air flow chamber extending from an interiorwall of the base member.
 21. The door of claim 20, wherein the air flowchamber comprises: a curved wall extending outside the outside wall ofthe base member; shaped side walls connecting the curved wall to thebase member; triangular side walls extending from the interior wall ofthe base member; and an angled front wall extending between thetriangular side walls having a lower edge intersecting the shroud. 22.The door of claim 21, further comprising a cut out in the air flowchamber for accommodating a motor.
 23. The door of claim 21, wherein thecut out has a shape of an upside down, truncated tear drop.
 24. The doorof claim 20, wherein the propeller comprises: a front hub plate facingthe processing chamber, the front hub plate having a central opening forreceiving an axle and a plurality of radiating petals, a rear hub platehaving a central opening for receiving the axle and a plurality ofradiating petals, and a plurality of radiating blades, each bladeattached at a first side edge to a petal of the front hub plate andattached at a second side edge to a petal of the rear hub plate.